Electrode having erectable lead

ABSTRACT

Disclosed is an electrode, such as an SCS paddle electrode, having a lead attached thereto along an interior portion of the electrode. The lead and electrode are configured such that the lead may be positioned generally coplanar with a top surface of the electrode, and may likewise be erected from such coplanar orientation up and away from the top surface of the electrode. Thus, the lead can maintain the typical configuration of emerging from the back end of the electrode, but because at least portions of the lead are not permanently bonded into the electrode paddle, the lead (when desired) can be pulled upward, with or without surrounding strain relief material, to emerge from the top surface of the paddle at an angle or curve to such top surface. This allows the base of the paddle to engage a bony opening, such as when the electrode is inserted into a patient&#39;s spine, skull, plane of fascia, etc.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.12/804,560 entitled “Electrode Having Erectable Lead,” filed with theU.S. Patent and Trademark Office on Jul. 23, 2010 (now U.S. Pat. No.8,676,346 issued Mar. 18, 2014), which application is based upon andclaims benefit of copending U.S. Provisional Patent Application Ser. No.61/228,399 entitled “Electrode Having Erectable Lead”, filed with theU.S. Patent and Trademark Office on Jul. 24, 2009 by the inventorherein, the specification of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to the field of implantablemedical electronic devices, such as electrical stimulators, epiduralelectrodes, defibrillators and pacemakers, and more particularly to anelectrode having an emerging lead capable of being erected away from theplane of the electrode.

BACKGROUND OF THE INVENTION

Many humans (and other mammals and animals) receive benefit fromimplantable medical devices that deliver electrical pulses to or recordfrom desired locations within their bodies. Such medical devices maycomprise, for instance, spinal cord stimulation (“SCS”) electrodes whichtypically comprise a small lead wire that is connected at one end to apower source and at the opposite end to a plurality of electricalcontacts configured to transfer an electrical signal to the tissues thatare to be stimulated. Those electrical contacts may, for instance, besituated in a paddle configured for implantation in a patient adjacentthe tissue that is to be stimulated, such as along the spinal cord of apatient. SCS paddles typically have the lead wire or wires emerging fromthe bottom edge of the paddle, in the same plane as the body of thepaddle. Also, typically there is a strain relief, molded along with thepaddle, which surrounds the emerging lead or leads for approximately 5-8mm, and beyond that the flexible leads continue onward to the powersource.

SCS paddles provided with such coplanar strain relief and leadassemblies can provide certain advantages. For instance, such assemblycan be advanced through an opening in the spinal canal (i.e., alaminectomy) upward or downward until the paddle and even the strainrelief and a portion of the lead disappear from view. This can be usefulin mapping stimulating contact positions higher or lower in the spinalcanal than would be allowed by the length of the paddle alone. Moreover,molding and overall manufacturing are more easily accomplished for suchconfigurations.

Unfortunately, however, such coplanar configurations also carrysignificant disadvantages. The placement of such components can be quitechallenging, as the health care provider must specifically place theelectrical contacts so that, when energized, they will record from orstimulate only the intended tissue, but not other tissue (stimulation ofwhich in turn may cause perceived paresthesia, muscle contractions oreven pain beyond that for which the patient originally soughttreatment). In the case of traditional paddle electrode configurations,the emerging lead wire and strain relief must be bent as they emergethrough an opening in bone, fascia or other tissue (for instance,laminectomy in the spine or burr hole in the skull), and to the extentthat they are elastic, this introduces a bending moment, which tends tomake the paddle migrate to one side or the other. Such migration willtypically require surgical revision to replace the paddle in the properposition. Moreover, the techniques used to anchor such electrodes inplace inside of the patient are insecure, such that the electrodes havea tendency to migrate away from the site at which they are originallyimplanted in the patient, at times in response to normal body movementof the patient. To the extent that it might not be anchored securely andcan migrate downward, the lowermost part of a traditionally configuredpaddle electrode can come up and out of the spinal canal or skull, suchthat this part is no longer useful. Still further, during implantation,it can be quite difficult to engage a traditionally configured paddleelectrode with the bony window formed by the laminectomy or burr hole,so as to mechanically lock the paddle in place within the epidural spaceof the spine or intracranially.

Attempts have previously been made to provide a paddle electrode inwhich the lead attaches to and emerges from the paddle along a face ofthe paddle, in turn reducing, at least to some extent, the bendingmoments that might be applied to the paddle from the lead. However, suchprior efforts have themselves carried disadvantages, in that theyprevent passage of the portion of the paddle at which the lead attachesabove or below the bony window created by the laminectomy, because thenearly perpendicular emerging lead wire blocks further progress as itruns into the bony edge.

It would therefore be beneficial to provide an electrode that is moreeasily implanted by the health care provider in the intended position,and that is less prone to migration from the intended implantation sitethan previously known electrodes.

SUMMARY OF THE INVENTION

Disclosed is an electrode, such as an SCS paddle electrode, having alead attached thereto along an interior portion of the electrode. Thelead and electrode are configured such that the lead may be positionedgenerally coplanar with a top surface of the electrode, and may likewisebe erected from such coplanar orientation up and away from the topsurface of the electrode. Thus, the lead can maintain the typicalconfiguration of emerging from the back end of the electrode, butbecause at least portions of the lead are not permanently bonded intothe electrode paddle, the lead (when desired) can be pulled upward, withor without surrounding strain relief material, to emerge from the topsurface of the paddle at an angle or curve to such top surface. Thisallows the base of the paddle to engage a bony opening, such as when theelectrode is inserted into a patient's spine, skull, plane of fascia,etc.

With respect to a particularly preferred embodiment of the invention, animplantable electrode is provided comprising an electrode body having afront end, a back end, a top surface, and a bottom surface, and a leadhaving an electrode engaging portion extending into said electrode bodyfrom the back end and fixed to the electrode body at least at a leadterminal point located between the front end and the back end, wherein asection of said electrode engaging portion of said lead is erectableaway from said top surface of said electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

The numerous advantages of the present invention may be betterunderstood by those skilled in the art by reference to the accompanyingdrawings in which:

FIG. 1 is a top view of an electrode according to one aspect of aparticularly preferred embodiment of the invention.

FIG. 2 is a side, cross-sectional view of the electrode of FIG. 1.

FIG. 3 is a cross-sectional view along section line A-A of FIG. 1.

FIG. 4 is a side, perspective view of the electrode of FIG. 1 placedinto a patient's spine.

FIGS. 5A and 5B are cross-sectional views of an electrode according toanother aspect of the invention.

FIG. 6 is a side view of an electrode according to yet another aspect ofthe invention.

FIG. 7 is a cross-section view of the electrode of FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

The following description is of a particular embodiment of theinvention, set out to enable one to practice an implementation of theinvention, and is not intended to limit the preferred embodiment, but toserve as a particular example thereof. Those skilled in the art shouldappreciate that they may readily use the conception and specificembodiments disclosed as a basis for modifying or designing othermethods and systems for carrying out the same purposes of the presentinvention. Those skilled in the art should also realize that suchequivalent assemblies do not depart from the spirit and scope of theinvention in its broadest form.

With regard to a particularly preferred embodiment of the invention, animplantable electrode is provided, such as a SCS paddle electrode,capable of being surgically implanted inside of a patient so as totransfer an electrical signal from a power source to targeted tissue inthe patient. The paddle electrode is particularly configured so as toallow the lead wire to lie flat and generally coplanar with a surface ofthe paddle in those applications where a coplanar configuration isdesired, but to likewise allow erection of the lead out of the plane ofthe paddle in those applications where an angled orientation between thelead and the paddle is desired.

With regard to a particularly preferred embodiment of the invention andwith reference to FIGS. 1 and 2, a paddle electrode 100 is shown havinga top surface 102, bottom surface 104, front end 106, and back end 108.A lead 110 enters the paddle electrode 100 through back end 108. Lead110 contains a plurality of wires 112 that engage electrical contacts114 situated on paddle electrode 100, and at an opposite end of lead 110connect to a power source (not shown) so as to convey an electricalsignal from such a power source to each of electrical contacts 114.

An electrode engaging portion 123 of lead 110 extends into paddleelectrode 100 through a hollow channel 120, which electrode engagingportion 123 extends from back end 108 into a central portion of the bodyof paddle electrode 100, and terminating in such central portion ofpaddle electrode 100 at a lead terminal point 121. A longitudinal slit122 likewise extends from back end 108 of paddle electrode 100 into suchcentral portion, and extends downward into top surface 102 of paddleelectrode 100 and into channel 120. Slit 122 thus provides an opening intop surface 102 of paddle electrode 100 through which lead 110 may bepulled, thus raising at least a section of electrode engaging portion123 of lead 110 out of the plane of the top surface 102 of paddleelectrode 100, while the forward-most end 124 of lead 110 (coincidingwith lead terminal point 121) remains affixed to and generally parallelto the major axis of paddle electrode 100.

FIG. 3 provides a cross-sectional view along section line A-A of FIG. 1of paddle electrode 100, in which it can be seen that slit 122 extendsdownward through top surface 102 of paddle electrode 100 and down tolead 110, thus allowing at least a section of electrode engaging portion123 of lead 110 to be pulled upward and away from paddle electrode 100.Thus, when circumstances so dictate, the healthcare provider may pullthe lead 110 upward so that a portion of lead 110 emerges from topsurface 102 at an angle or a curve. As shown in FIG. 4, this allows thebase of the paddle to mechanically engage a bony opening formed from alaminectomy procedure for purposes of inserting an electrode into apatient's spine. As those of ordinary skill in the art will appreciate,such application is not limited, however, to implantation of anelectrode in a patient's spine, and may likewise be used forimplantation of an electrode in a patient's skull, in a plane of fascia,subcutaneously, or in any other tissue.

With regard to another aspect of an embodiment of the invention and withparticular reference to FIGS. 5A and 5B, paddle electrode 100 may beprovided with a keel 200 positioned on top side 102 of paddle electrode100. Once again, an electrode engaging portion of lead 110 extends intokeel 200 through a hollow channel 220 in the same manner as describedabove. In this case, slit 122 may be provided extending downward fromthe top surface of keel 200 to lead 110, in turn allowing at least asection of the electrode engaging portion of lead 110 to be pulledupward and away from paddle electrode 100.

With regard to another aspect of an embodiment of the invention and withparticular reference to FIGS. 6 and 7, paddle electrode 100 may again beprovided a keel 200. Instead of a slit as shown in FIGS. 1-5, and whilelead 110 extends into and is affixed to keel 200, a strain reliefportion 202 of keel 200 is separable from the top surface 102 of paddleelectrode 100. In this configuration, lead 110 may remain within thekeel 200 as it separates from top surface 102 of paddle electrode 100,so that they might be erected together, with the portion 202 of keel 200serving as strain relief.

A membrane may optionally be provided between keel 200 and top surface102 of paddle electrode 100, which membrane maintains continuity betweenthe lead 110 and the paddle electrode 100 when they diverge. The purposeof such web is to prevent tissue ingrowth which might make removal ofthe paddle electrode 100 more difficult once the patient's bodyencapsulates it in scar. Omitting this feature, on the other hand, wouldlead to greater tissue ingrowth and stability.

Optionally, adhesive may be used to bond lead 110 into paddle electrode100 at or before the time of implantation, in the case that using it inthe erected position is not contemplated. It is envisaged, however, thatthe above-described construction will be sufficiently secure, when lead110 is simply engaged in paddle electrode 100, that this is notessential.

It shall be understood that various other characteristics of the novelerectable lead electrode of the current invention may be changed withoutdeparting from the scope and spirit of the present invention. Forinstance, the material composition of the paddle electrode may compriseany preferably chemically, electrically, and biologically inertmaterial, such as medical grade, inert, elastomeric polymer or asilicone elastomer, or any other similarly configured flexible materialsuitable for surgical implantation and for use with electrical contacts114. The material composition of the lead 110 may be similar to ordifferent from that of the paddle electrode 100. In addition, while theexemplary embodiments show a paddle electrode of generally constantproportion and configuration throughout, it is contemplated that partsof the paddle electrode may include varying proportions orconfigurations.

It is believed that the present invention and many of its attendantadvantages will be understood by the forgoing description. It is alsobelieved that it will be apparent that various changes may be made inthe form, construction and arrangement of the components thereof withoutdeparting from the spirit and scope of the invention or withoutsacrificing all of its material advantages. The form herein beforedescribed is merely an explanatory embodiment thereof.

I claim:
 1. An implantable electrode comprising: an electrode paddlebody having a front end, a back end, a top surface, and a bottomsurface; a keel on the top surface of said electrode body; and a leadhaving an electrode engaging portion extending into said keel andaffixed to said electrode paddle body, said electrode engaging portionof said lead extending into said keel from a back end of said keeladjacent the back end of said electrode paddle body and fixed to theelectrode paddle body at a lead terminal point located between the frontend and the back end of said electrode paddle body, wherein saidelectrode engaging portion is configured to sit entirely within the keelwhen in a first position; wherein a section of said electrode engagingportion of said lead is erectable away from said first position to asecond position in which said section of said electrode engaging portionextends away from said electrode paddle body.
 2. The implantableelectrode of claim 1, further comprising a plurality of electricalcontacts within one of said top surface and said bottom surface of saidelectrode, and a plurality of wires extending from said lead at saidlead terminal point to said plurality of electrical contacts.
 3. Theimplantable electrode of claim 1, wherein said lead terminal point islocated at a point on said electrode body that is closer to a midpointof said electrode body between said front end and said back end than tothe back end of said electrode body.
 4. The implantable electrode ofclaim 1, said keel further comprising an elongate strip positioned onsaid top surface of said electrode body and having a width less than awidth of the top surface of said electrode body.
 5. The implantableelectrode of claim 4, wherein at least a portion of said keel is fixedto the top surface of said electrode body.
 6. The implantable electrodeof claim 1, wherein said lead extends into a hollow channel extendinginto said keel from the back end of said electrode body to said leadterminal point.
 7. The implantable electrode of claim 6, said keelfurther comprising a longitudinal slit on a top surface of said keelextending from said top surface of said keel to said hollow channel. 8.The implantable electrode of claim 7, wherein said section of saidelectrode engaging portion of said lead is erectable outward from saidhollow channel through said longitudinal slit and away from said topsurface of said electrode body.
 9. The implantable electrode of claim 6,wherein said keel is directly attached to said top surface of saidelectrode body along only a first portion of the length of said keel,and is not directly attached to said top surface of said electrode bodyalong a second portion of the length of said keel.
 10. The implantableelectrode of claim 9, wherein said section of said electrode and saidsecond portion of said keel are extendable away from said top surface ofsaid electrode body.
 11. The implantable electrode of claim 10, furthercomprising a membrane situated between said top surface of saidelectrode body and said second portion of said keel.